Medizinische/biologische Studie (experimentelle Studie)

Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats chronically exposed to 836 MHz modulated microwaves med./bio.

[Spontane und Nitrosoharnstoff-induzierte Primärtumoren des Zentralnervensystems bei Fischer 344-Ratten, die chronisch bei modulierten 836 MHz-Mikrowellen exponiert wurden]

Von: Adey WR, Byus CV, Cain CD, Higgins RJ, Jones RA, Kean CJ, Kuster N, MacMurray A, Stagg RB, Zimmerman G, Phillips JL, Haggren W

Veröffentlicht in: Radiat Res 1999; 152 (3): 293-302

Referenz im RIS-Format herunterladen

Ziel der Studie (lt. Autor)

Es sollte bewertet werden, ob auf ein TDMA (Time Division Multiple Access)-Handy in einem Tiermodell einige der definierten Kriterien bekannter neurokarzinogener Mittel (in diesem Fall ENU (Ethylnitrosoharnstoff, ein Karzinogen)) zutreffen. Dazu gehört 1) ein konsequentes Vermögen, die Tumor-Inzidenz zu erhöhen, 2) eine Reduzierung der Latenzzeit, 3) die Feststellung einer direkten Dosis-Wirkungs-Beziehung, 4) eine Verschiebung in Richtung zu mehr anaplastischen Tumortypen und 5) eine erhöhte Empfindlichkeit von fötalen Geweben gegenüber Neuro-Karzinogenen im Vergleich zu voll entwickeltem (reifem) Gewebe.

Endpunkt

Krebs: ZNS-Tumoren

Exposition/Befeldung (teilweise nur auf Englisch)

- Mikrowellen
- TDMA
- Mobilfunk
- NADC

Exposition	Parameter
Exposition 1: 836,55 MHz Modulationsart: gepulst Expositionsdauer: kontinuierlich für etwa 25 Tage, siehe add. information	-
Exposition 2: 836,55 MHz Modulationsart: gepulst Expositionsdauer: täglich wiederholte intermittierende Exposition, 7,5 min an/aus, 2 h/Tag, 4 Tage/Woche für bis zu 680 Tage, siehe add. information	Leistung: 2,5 W (± 0,1 W) SAR: 1,4 W/kg Mittelwert über Masse (Gehirn) (Männchen 250 g bei 30 cm) SAR: 1,2 W/kg Mittelwert über Masse (Gehirn) (Männchen 450 g bei 45 cm) SAR: 1,1 W/kg Mittelwert über Masse (Gehirn) (Weibchen 150 g bei 30 cm) SAR: 1 W/kg Mittelwert über Masse (Gehirn) (Weibchen 250 g bei 45 cm)

Allgemeine Informationen

Rats were assigned to four experimental groups: Sham/Sham, Sham/Field, ENU/Sham and ENU/Field. A single dose of ENU was applied on gestation day 18 via the tail vein. Buffer alone was applied to the sham-injected groups.

Exposition 1

Hauptcharakteristika

Frequenz	836,55 MHz
Typ	elektromagnetisches Feld
Charakteristik	Fernfeld
Polarisation	zirkular
Expositionsdauer	kontinuierlich für etwa 25 Tage, siehe add. information

Modulation

Modulationsart	gepulst
Tastgrad	33,33 %
Folgefrequenz	50 Hz
Zusatzinfo	NADC with π/4 DQPSK

Expositionsaufbau

Expositionsquelle	Dipolantenne Hornantenne
Kammer	Far field conditions were simulated with an approx. plane wave in a large tapered horn radiator of square aperture (2 x 2 m²) and 4.2 m length (about 12 wavelengths). Circular polarization was achieved using crossed dipole antennae placed in front of a ground plane at the apex of the horn and phase-shifted antenna feeds.
Aufbau	Rat cages were positioned (not randomized daily) in a vertically oriented 3 x 3 matrix at the aperture of the horn in a "target chamber" that was 2.5 m square and 1.5 m deep, and lined with RF-absorbing foam. Sham exposures were performed in a square chamber of identical dimensions and materials, but the tapered section was truncated to 58 cm.
Zusatzinfo	Far field exposure of rats in their home cages began on gestation day 19 and continued until the pups were aged 21 days (about 25 days in total).

Parameter

Für diese Exposition sind keine Parameter spezifiziert.

Mess- und Berechnungsdetails

Plane wave equivalent power densities were measured using an electric field probe and meter unit. Wavefront circularity (axial ratio) was within 2.3 dB, and power density was within 1.6 dB across the cage exposure area.

Exposition 2

Hauptcharakteristika

Frequenz	836,55 MHz
Typ	elektromagnetisches Feld
Charakteristik	Nahfeld
Polarisation	nicht spezifiziert
Expositionsdauer	täglich wiederholte intermittierende Exposition, 7,5 min an/aus, 2 h/Tag, 4 Tage/Woche für bis zu 680 Tage, siehe add. information

Modulation

Modulationsart	gepulst
Tastgrad	33,33 %
Folgefrequenz	50 Hz
Zusatzinfo	NADC with π/4 DQPSK

Expositionsaufbau

Expositionsquelle	plastic-encapsulated half-wave sleeved dipole
Kammer	Twelve carousel exposure platforms were used each with 10 rats confined in PVC tubular restraints of different sizes and oriented radially around a central antenna. The antennas of adjacent carousels were spaced 1.7 m apart. Sham exposure was performed in identical carousels located in a different room.
Aufbau	The distance to the antenna from the tip of the nose was 30 mm from weaning to 120 days, and 45 mm thereafter.
Zusatzinfo	Near field exposure began at age 33 days and was performed on 4 consecutive days weekly until termination of the experiment at 709-712 days of age (376 exposures in total).

Parameter

Messgröße	Wert	Typ	Methode	Masse	Bemerkungen
Leistung	2,5 W	-	-	-	± 0,1 W
SAR	1,4 W/kg	Mittelwert über Masse	berechnet	Gehirn	Männchen 250 g bei 30 cm
SAR	1,2 W/kg	Mittelwert über Masse	berechnet	Gehirn	Männchen 450 g bei 45 cm
SAR	1,1 W/kg	Mittelwert über Masse	berechnet	Gehirn	Weibchen 150 g bei 30 cm
SAR	1 W/kg	Mittelwert über Masse	berechnet	Gehirn	Weibchen 250 g bei 45 cm

Zusätzliche Parameterdetails

SARs indicated are "slot" average values, time averaged values are one third of these. Ambient ELF magnetic fields measured with a gaussmeter above each antenna ranged from <0.01 to 0.04 µT rms. Ambient static magnetic fields were between 31 and 39 µT.

Mess- und Berechnungsdetails

An RF power meter and RF sensor were coupled directly to the feedline of the antenna connector. Antennas were tested for impedance matching (VSWR) and feedpoint impedances. Field patterns have been modelled in detail in the reference article. Dosimetric assessments were made by three different techniques: numerical modelling (FDTD and FIT) based on MRI data sets of a rat cadaver (verified by electric probe measurements in the brain), thermometric probes and thermography. The uncertainty of the numerical dosimetry was estimated to be less than ± 1.5 dB. Uncertainty in thermography is less than ± 3 dB.

Referenzartikel

Burkhardt M et al. (1997): Exposure setup to test effects of wireless communications systems on the CNS

Exponiertes System:

Methoden Endpunkt/Messparameter/Methodik

Krebs: ZNS-Tumor (Anzahl und Inzidenz von ZNS Primär-Tumoren; Anzahl und Klassifizierung von Tumor-Subtypen); große Granulozyten-Leukämie
Körpergewicht; Untersuchung der Entwicklung klinischer Zeichen (z.B. Paralyse, Augenausfluss, Kopf-Schieflage, plötzliche Verhaltensänderungen); Überlebensrate

Untersuchtes System:

Gewebeschnitt (in vitro)
Blutproben; Rückenmarks-Teilstücke
Untersuchung am lebenden Organismus

Untersuchtes Organsystem:

Gehirn/ZNS

Untersuchungszeitpunkt:

während der Befeldung
nach der Befeldung

Hauptergebnis der Studie (lt. Autor)

Die Studie zeigt keine erhöhte Tumorentstehung im Säugetier-ZNS bei Exposition bei TDMA-Signalen. Insgesamt wiesen die TDMA-Feld-exponierten Tiere Tendenzen in Richtung reduzierter Inzidenz spontaner oder ENU (Ethylnitrosoharnstoff)-induzierter ZNS-Tumoren auf.

Studienmerkmale:

medizinische/biologische Studie
experimentelle Studie
Voll-/Hauptstudie

Studie gefördert durch

Motorola

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